1. Field of the Invention
The present invention relates to a linear guide device provided in a guide portion of a machine, e.g., a machine tool, such as a cutting machine or a grinding machine, or an industrial machine, such as a wood working machine, a cutter, or an injection molding machine, and used to linearly move a movable base, such as a table.
2. Description of the Related Art
In a conventional linear guide device, a saddle-like slider is provided with a connection path, and balls circulating through this connection path are caused to roll on a track surface of a track recess provided on a side surface of a rail so that the slider can move linearly on the rail, and a rail cover whose longitudinal edge portions are bent by an angle smaller than 90 degrees is engaged with an undercut provided on the top of the upper side surfaces (on both sides of the rail, preventing intrusion of dust, product chips, etc. by means of seals provided at the front and rear ends with respect to the slider moving direction (see, for example, U.S. Pat. No. 5,575,566).
Further, in another conventional linear guide device, a plate-like rail cover is glued by adhesive to the upper surface of a rail of a similar linear guide device to thereby prevent intrusion of cutting chips or the like (see, for example, JP 01-140936 A).
Further, in a still another conventional linear guide device, a rail cover covering the upper surface of a rail of a similar linear guide device is engaged with or screwed to a track surface by means of cover stoppers provided at both ends with respect to the moving direction of a slider (referred to as the slider moving direction) to prevent relative movement of the rail cover and the rail (see, for example, U.S. Pat. No. 6,513,976).
Generally speaking, a track recess forming a track surface provided on a side surface of a rail is formed by grinding, and, to achieve an improvement in machining precision and a reduction in machining man-hours, it is desirable to form the track recess and the side surface at one time by using a form grind stone.
However, in the technique as disclosed in U.S. Pat. No. 5,575,566, a step-like undercut is provided on the top of the rail upper side surface to allow engagement of the rail cover, so that it is necessary to form fine protrusions and recesses on the rail side surface and it is necessary for the form grind stone to be of a configuration with fine protrusions and recesses; to avoid damaging these fine protrusions and recesses during grinding, it is rather difficult to increase the grinding speed, resulting in a deterioration in machining efficiency.
Further, in the technique as disclosed in JP 01-120936 A, the plate-like rail cover is glued to the rail upper surface by adhesive to cover the upper surface of the rail, so that, while effective when used in a dry environment, when used in an environment where it is exposed to a water-soluble substance, such as a coolant cutting liquid for use in a machine tool, the device has a problem in that the aqueous solution permeates the adhesive between the plate-like rail cover and the rail upper surface to thereby deteriorate the adhesion property of the adhesive, resulting in the rail cover being raised or detached.
Further, in the technique as disclosed in U.S. Pat. No. 6,513,976, the cover stoppers are engaged with or screwed to the rail track surface to fix the rail cover covering the rail upper surface, so that a dent or flaw due to the pressurizing force or the screw fastening force is generated on the track surface, with the result that the rolling members are subject to damage at the time of movement of the slider or at the time of re-assembly after dismantling, which may lead to generation of noise, an increase in sliding resistance, etc. during sliding movement of the slider.